For a variety of reasons, occlusions often develop in narrow body lumens (i.e., the channel of a tubular-shaped anatomical structure, such as the fallopian tubes, intestines, and coronary arteries) and have medically-relevant consequences on the body. Conventional techniques employed to maintain the health of fallopian tubes, as an example of a narrow body lumen, are described below.
Fallopian tubes are vessel-like, non-fluid filled structures that extend from the uterus to the ovaries. On average, fallopian tubes measure between eight and ten centimeters in length. The inner diameter of the tube varies significantly depending on the segment of the tube, with a minimum inner diameter of approximately one millimeter and a maximum of six millimeters. Along the length of the lumen of the fallopian tube millions of microscopic hair-like cilia pulsate in wave-like motions at the rate of hundreds of times per second. This motion assists the egg, delivered from the ovaries during ovulation, in passing through the tube to the uterine cavity. Cells located in the tube's inner lining (endothelium) supply the egg with vital nourishment and provide lubrication along the path. It is within the fallopian tube that the sperm first contacts the egg. If the egg is not fertilized within twenty-four to thirty-six hours of reaching the fallopian tube, the egg deteriorates and is removed from the tube by the body's immune system.
Disease of fallopian tube often presents as occlusion or thickening of the fallopian tube wall and can be caused by infection as well as scarring. In particular, pelvic inflammatory disease (PID), urinary tract infections (UTI) as well as sexually transmitted infections (STI) may cause severe inflammation that in turn blocks the tube. Endometriosis may also cause occlusion when the uterine lining grows into the fallopian tube. An appendectomy or other abdominal surgery may further similarly lead to occluded fallopian tubes. Regardless of the manner in which it is formed, an occlusion can lead to a hydrosalpinx, where the tube increases in diameter because it is filled with fluid. The presence of fluid prevents both the egg and sperm from traveling through the fallopian tube, preventing fertilization. It is believed that hydrosalpinx can reduce the success rate of in-vitro fertilization by up to 8%.
In the US alone, there are at least seven million cases of infertility annually and an estimated 25-40% of these cases are caused by fallopian tube occlusion or disease. Hysterosalpingogram (HSG), a procedure most commonly utilized to diagnose fallopian tube disease, requires a radiologist to inject dye into the uterus under x-ray guidance. The dye enters the fallopian tube through the ostia (openings) located in the uterus. If a woman's fallopian tubes are patent (open), dye will flow into the peritoneal cavity. In order to visualize the fluid path, a series of timed x-rays are taken.
Unfortunately, this procedure suffers from several drawbacks. By way of example, HSG suffers from a high false negative rate of 30% and a high false positive rate of 40% due to tubal spasms or shadow (noise) in the x-rays. This often necessitates further procedures. This high rate of inaccuracy is also partly due to the fact that radiologists are not as intimate with the tortuosity and topography of the fallopian tube as gynecologist or reproductive endocrinologist.
As another example of a drawback, HSG is not conducted in-office by a gynecologist or reproductive endocrinologist, the primary caretaker of the patient, as it necessitates a substantial investment in x-ray capital equipment mostly found in hospitals. The patient typically first visits a gynecologist, who conducts a series of blood tests and determines whether HSG is necessary. If it is deemed necessary, then the patient schedules an appointment with the radiologist to have the HSG procedure administered. At the conclusion of the first procedure, the patient returns either to the gynecologist or reproductive endocrinologist to discuss the results. Because of the high inaccuracy rate associated with the HSG, the patient often returns to the radiologist for a second procedure, creating additional unnecessary costs for both the patient and hospital.
As yet another example, patients often complain of pain and some are allergic to the dye used during the procedure. Furthermore, HSG must be conducted before day 12 of a woman's menstrual cycle because the dye may harm a potential full term pregnancy, which limits options for both doctor and patient and further extends the waiting period for a full infertility diagnosis, which is emotionally taxing to the patient and family.
To overcome these drawbacks, different direct visualization techniques have been attempted. FIG. 1 shows an endoscope, which uses conventional optical fiber imaging technology, as an exemplar attempt to achieve direct visualization of the fallopian tubes. In this figure, a female reproductive anatomy 10 undergoing imaging includes fallopian tubes 12, ovaries 14, uterus 16, uterine cavity 22, cervix 28 and fimbria 30. An imaging catheter shaft 20 is introduced into a fallopian tube, which has a consistency of a wet paper towel. Catheter shaft 20 passes through fallopian tube ostia in the uterus 18, beyond which point the fallopian tube 12 is narrow and tortuous.
Unfortunately, the wet-paper-towel consistency does not provide adequate tactile feedback to a physician, who navigates catheter 20 through fallopian tube 12. As a result, during the imaging procedure, the physician is not aware of the undue pressure exerted against the fallopian tube, leading to perforation 24. To this end, FIG. 1 shows a portion of catheter 26 protruding out of perforation 24 in fallopian tubes 12. Perforation of the fallopian tube may prevent eggs from the ovaries 14 of the patient from reaching the uterus 16 for fertilization, making perforation an unacceptable clinical adverse event in a patient who is actively attempting to conceive. In addition to running the risk of perforating the fallopian tubes, the imaging procedure described above involves several steps and is therefore viewed by physicians as convoluted and difficult to perform correctly. Furthermore, the wet paper towel consistency of the fallopian tubes prevents the attempted imaging procedure from obtaining a clear, focused image. Specifically, during imaging, the wet paper towel consistency causes the fallopian tubes' walls to “fold” over the endoscope's tip, making it difficult to maintain a sufficient distance between the endoscope's tip and the walls of the fallopian tubes to focus and take a clear picture.
Therefore, what is needed is a novel diagnostic and therapeutic system and method which allows for effective maintenance of a narrow body lumen, without suffering from the drawbacks encountered by the current and attempted systems and methods described above.